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A coalition of environmental groups appealed a court rejection of their challenge to California's plan to build Sites Reservoir in a valley north of Sacramento, its first new major reservoir in decades.

They argue the project would harm Sacramento River ecosystems and threaten imperiled . The groups include the Center for Biological Diversity, Sierra Club, Friends of the River, California Sportfishing Protection Alliance, California Water Impact Network and Save California Salmon.

"For the sake of the Delta community and the fish and wildlife already struggling in this sensitive ecosystem, I hope the true environmental harms of this reservoir will be taken seriously," said John Buse, senior counsel at the Center for Biological Diversity.

"There are still numerous hurdles before the Sites Reservoir and that's because the state's strong environmental laws demand a thorough review for potentially damaging projects."

In a May ruling, a Yolo County Superior Court judge sided against advocates and determined that the project's environmental review was sufficient. Gov. Gavin Newsom celebrated the decision, saying the project had cleared a major hurdle.

He had sought to speed the California Environmental Quality Act process through an infrastructure streamlining law that requires courts to decide on within 270 days when feasible.

"California needs more water storage, and we have no time to waste—projects like the Sites Reservoir will capture rain and snow runoff to supply millions of homes with ," Newsom said after the ruling.

With a maximum capacity of 1.5 million acre-feet of water, state officials say at its maximum, the proposed $4.5 billion will store enough water to supply the yearly usage of 3 million households.

To do so, state agencies would inundate nearly 14,000 acres of ranch lands in Glenn and Colusa counties with water diverted from the Sacramento River through new a system of dams, pipelines and a bridge.

Environmental advocates with the group Friends of the River and other groups have long opposed the project, voicing concerns that diverting water would harm struggling fish populations and the ailing ecosystem of the Sacramento-San Joaquin River Delta.

They filed their lawsuit in December, arguing that the project underestimated its environmental impacts and failed to consider alternatives to achieving the same amount of .

But the court found that the environmental review of the project and consideration of alternatives was sufficient, and within jurisdiction of the Sites Reservoir Authority.

Before construction begins, the project must still acquire a multitude of state and federal permits. That includes a water rights application with the State Water Resources Control Board. That public proceeding will consider fish and wildlife protection.

A series of several public hearings at the Water Board began June 17 and are scheduled to continue through October.